The game of golf has always been heavily related to the golf equipment used to play this game. Although the game of golf has deep roots keeping with the tradition of the game, golf club technology has come a long way to make the game of golf easier and more enjoyable for the average golfer.
The golf clubs of today have developed significantly to include numerous performance enhancing features such as creating an oversized hollow club head, creating a club with additional weights towards the bottom of the club to help promote launch, even including unconventional changes varying the shapes and geometries of a golf club head to square shapes and triangular shapes in order to improve performance of a golf club head. These types of technological advancement may be especially prevalent in a driver type golf club head, wherein we've seen drivers transition from a solid wooden persimmon golf club head to a hollow metallic golf club heads with volumes reaching close to 460 cubic centimeters; all for the purpose of improving performance of the driver type golf club head.
One of the main objectives of a driver type golf club is to hit a golf ball as far as possible while keeping the golf ball in a semi-straight flight path. Three major factors; namely launch angle, ball speed and spin rate, contribute to length of travel of a golf ball after it is struck by a golf club. Focusing on one of the most influential factors, ballspeed may generally be a function of the total kinetic energy imparted to the ball as it is being struck by a golf club deriving its potential energy from the golfer's golf swing. This kinetic energy within the golf club head may also be known as elastic strain energy and this energy may generally be related to the deformation of the golf club head as well as the golf ball. After impact, the kinetic energy generated by the golf club is transferred in the form of translational and rotational velocity on the ball causing the golf ball to fly off the face of the golf club head; correlating to what is commonly known as the ballspeed. However, because the collision between the golf club and the golf ball is not perfectly elastic, a portion of energy is lost and dissipated during the impact resulting in club head vibration as well as viscoelastic compression and relaxation of the ball.
In order to increase the ball speed coming off the striking surface of a golf club, it may generally be desirable to minimize energy lost between the golf ball and the golf club. One method of minimizing the energy lost between the golf ball and the golf club is to decrease the thickness of the face of the golf club; as decreasing the thickness of the face of the golf club head will cause the face of the golf club to deform like a trampoline, alleviating some of the viscoelastic compression and relaxation of the golf ball. Viscoelastic compression and relaxation of the golf ball, although difficult to observe using the naked eye, may generally be one of the major contributors to the amount of energy lost during impact. However, there is a limit as to how thin one can make the striking face of a golf club head, as a striking face that is made too thin may crack and break when subjected to the tremendous and continuous impacts between a golf club and a golf ball. Hence it can be seen that there is a diametrically opposing need to make the striking face of the golf club as thin as possible to maximize performance while at the same time making the striking face as thick as possible for durability.
The requirement for a golf club head striking face to be sufficiently thick and durable has been identified by U.S. Pat. No. 6,595,057 to Bissonnette et al. entitled Golf Club Head With a High Coefficient of Restitution when it states that a golf club head must be strong enough to withstand the impact forces that occur during collision between the head and the ball. The loading that occurs during this transient event can peak over 2,000 lbs and cause an acceleration of the golf ball that is four orders of magnitude than the acceleration of gravity. It is not unusual for club heads of hollow metal woods, produced from titanium, to have a uniform face thickness exceeding 0.15 inches.
U.S. Patent Publication No. 2008/0146374 to Beach et al. entitled Golf Club-Head Having a Particular Relationship of Face Area to Face mass also identifies this very important issue of durability and endurance by discussing how conventional ways of removing mass from the face plate are not always successful; if too much mass is removed from the face plate, the structural mass of the strike plate may be excessively compromised, which can result in the striking plate being too fragile and/or its COR being too high.
In fact, durability and endurance is such an important characteristic of a golf club, U.S. Pat. No. 6,348,011 to Reyes et al. entitled Texture Coating for Golf Club specifically address this issue by providing for a golf club having a texture coating exhibiting improved durability and aesthetic appearance on golf club head surfaces in order to improve the ability of a striking face of a golf club head to withstand the impact with a golf ball.
However, the limitations of durability and endurance are premised upon the conventional thinking that the striking surface of a golf club has to be sufficiently durable and strong so that it will not break or crack when striking a golf ball over a certain number of shots. Even more, golf clubs are often over-designed in a way so they will survive numerous strikes by an extremely strong hitter in order to ensure that the striking surface of the golf club will not break under any conceivable playing conditions, when the majority of the consuming public do not impart a fraction of the forces generated by an extremely strong hitter.
Alternatively, if a golf club is not constrained by such a conventional thought process, the striking face of the golf club could be designed in a way that it will be intended to fail, so long as the striking face is removable and maybe even disposable. This alternative approach to golf club design allows for improvement in the performance of the golf club by allowing the striking face to be manufactured much thinner with a larger sweet spot, so long as the striking face that eventually breaks may be removed and replaced. Sweet spot, as generally known in the golf industry, refers to the portion of the striking area that yields approximately the same ball speed when striking a golf ball. It can be seen from the above that there is a need in the field for golf club heads wherein the face of the golf club is removable and disposable allowing the striking face to be thinned to improve performance. More specifically, there is a need in the field for a golf club with a removable and disposable face allowing for face thicknesses of less than about 0.15 inches. Even more specifically, there is a need in the field for a golf club with removable and disposable face with a larger more uniform sweet spot that maintains 99% of the maximum Contact Time (CT) for at least 6% of the entire frontal striking surface.